A pocket calculator (computer, mobile phone, etc.) should do it. A minute is a sixtieth of a degree, so take the decimal part of the position in degrees and multiply it by 60 to convert it to minutes. Thus in the example that you gave, latitude 42.358372° *42.358372°* becomes 42° *42° (0.358372 x 60)', 60)'*, or 42°21.502'. *42°21.502'*.
Next, you need to know that negative latitude means South of the equator, and negative longitude means West of the Greenwich meridian. That is simply a convention adopted by all geographers. geographers.
So your position becomes N42°21.502' W8°51.485'. *N42°21.502' W8°51.485'*. That is the format most commonly used for navigation at sea, where it is useful because a minute of latitude is a nautical mile. The same format is used for geocaching.
You can, if you wish, convert the minutes to minutes and seconds in the same way, as a second is simply a sixtieth of a minute. Expressed in that way, the position that you used as an example is N42°21'30" W8°51'29".
*N42°21'30" W8°51'29"*.
It's in the coastal waters off North West Spain.
